The patch titled
Subject: mm/ZONE_DEVICE/free-page: callback when page is freed
has been added to the -mm tree. Its filename is
mm-zone_device-free-page-callback-when-page-is-freed-v3.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-zone_device-free-page-callback-when-page-is-freed-v3.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-zone_device-free-page-callback-when-page-is-freed-v3.patch
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------------------------------------------------------
From: Jérôme Glisse <jglisse@xxxxxxxxxx>
Subject: mm/ZONE_DEVICE/free-page: callback when page is freed
When a ZONE_DEVICE page refcount reach 1 it means it is free and nobody
is holding a reference on it (only device to which the memory belong do).
Add a callback and call it when that happen so device driver can implement
their own free page management.
Link: http://lkml.kernel.org/r/1489680335-6594-4-git-send-email-jglisse@xxxxxxxxxx
Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memremap.h | 6 ++++++
kernel/memremap.c | 11 ++++++++++-
2 files changed, 16 insertions(+), 1 deletion(-)
diff -puN include/linux/memremap.h~mm-zone_device-free-page-callback-when-page-is-freed-v3 include/linux/memremap.h
--- a/include/linux/memremap.h~mm-zone_device-free-page-callback-when-page-is-freed-v3
+++ a/include/linux/memremap.h
@@ -35,19 +35,25 @@ static inline struct vmem_altmap *to_vme
}
#endif
+typedef void (*dev_page_free_t)(struct page *page, void *data);
+
/**
* struct dev_pagemap - metadata for ZONE_DEVICE mappings
+ * @page_free: free page callback when page refcount reach 1
* @altmap: pre-allocated/reserved memory for vmemmap allocations
* @res: physical address range covered by @ref
* @ref: reference count that pins the devm_memremap_pages() mapping
* @dev: host device of the mapping for debug
+ * @data: privata data pointer for page_free
* @flags: memory flags see MEMORY_* in memory_hotplug.h
*/
struct dev_pagemap {
+ dev_page_free_t page_free;
struct vmem_altmap *altmap;
const struct resource *res;
struct percpu_ref *ref;
struct device *dev;
+ void *data;
int flags;
};
diff -puN kernel/memremap.c~mm-zone_device-free-page-callback-when-page-is-freed-v3 kernel/memremap.c
--- a/kernel/memremap.c~mm-zone_device-free-page-callback-when-page-is-freed-v3
+++ a/kernel/memremap.c
@@ -190,7 +190,14 @@ EXPORT_SYMBOL(get_zone_device_page);
void put_zone_device_page(struct page *page)
{
- page_ref_dec(page);
+ int count = page_ref_dec_return(page);
+
+ /*
+ * If refcount is 1 then page is freed and refcount is stable as nobody
+ * holds a reference on the page.
+ */
+ if (page->pgmap->page_free && count == 1)
+ page->pgmap->page_free(page, page->pgmap->data);
put_dev_pagemap(page->pgmap);
}
@@ -329,6 +336,8 @@ void *devm_memremap_pages(struct device
pgmap->ref = ref;
pgmap->res = &page_map->res;
pgmap->flags = MEMORY_DEVICE;
+ pgmap->page_free = NULL;
+ pgmap->data = NULL;
mutex_lock(&pgmap_lock);
error = 0;
_
Patches currently in -mm which might be from jglisse@xxxxxxxxxx are
mm-memory-hotplug-convert-device-bool-to-int-to-allow-for-more-flags-v3.patch
mm-put_page-move-ref-decrement-to-put_zone_device_page.patch
mm-zone_device-free-page-callback-when-page-is-freed-v3.patch
mm-zone_device-unaddressable-add-support-for-un-addressable-device-memory-v3.patch
mm-zone_device-x86-add-support-for-un-addressable-device-memory.patch
mm-migrate-add-new-boolean-copy-flag-to-migratepage-callback.patch
mm-migrate-new-memory-migration-helper-for-use-with-device-memory-v4.patch
mm-migrate-migrate_vma-unmap-page-from-vma-while-collecting-pages.patch
mm-hmm-heterogeneous-memory-management-hmm-for-short.patch
mm-hmm-mirror-mirror-process-address-space-on-device-with-hmm-helpers.patch
mm-hmm-mirror-helper-to-snapshot-cpu-page-table-v2.patch
mm-hmm-mirror-device-page-fault-handler.patch
mm-hmm-migrate-support-un-addressable-zone_device-page-in-migration.patch
mm-migrate-allow-migrate_vma-to-alloc-new-page-on-empty-entry.patch
mm-hmm-devmem-device-memory-hotplug-using-zone_device.patch
mm-hmm-devmem-dummy-hmm-device-for-zone_device-memory-v2.patch
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